Since I had my 19 advanced, I notice there is always some faint stereo noise in the cabin when the car is turned off. Today, I get close to the speakers on the door and was surprises how loud that noise is. It sounds like those speakers white noise when they are turned on. I am concerned that it is constantly draining my battery since it never turns off even with the car locked. I first thought it was the ANC making the noise but the noise persists even when I unplug the ANC. Has anyone had this problem before?

 

Yes, I hear it too. White noise. I believe it must shut off sometime as my car may sit for 4 days at a time due to my travel.
In the past I had a stereo amp that when shut down it would take time to turn fully off. Perhaps it is this sort of thing.